Apparatus for testing a credit card

ABSTRACT

Apparatus for testing a credit card having a coating of a substance which when treated sufficiently permanently and irreversably changes from a first state having one characteristic of reflectivity for visible light components incident thereon to a second state having a second characteristic of reflectivity for the light components. Preferably, in the first state the substance is highly light reflective and reflects light of different wavelengths unequally, and in the second state the substance is light transparent. Treating of the substance is accomplished by heating the substance, preferably with a high intensity light beam. Authenticity of the credit card is achieved by first measuring the amplitude of visible light components (colors) reflected by the substance when the substance is treated initially, and by a later spectral reflectance test after additional treating which, by sensing the change in amplitude of a previously highly reflected visible light component, indicates that the substance has changed to the second state in response to the additional treating. The authentification apparatus includes a light source for treating a selected area of the coating and a plurality of photoresponsive elements each responsive to light of a selected wave length and connected in electrical integration networks. The integration networks transforms the amplitude representative signals supplied thereto to time amplitude varying signals which are supplied to flip-flop circuits of a logic circuit which also includes at least one nor gate and a latch circuit. If the credit card is authentic, the amplitudes of the output signals of the integration networks increase and decrease in the proper sequence to control the logic circuit such that it produces an acceptance or &#39;&#39;&#39;&#39;authentic&#39;&#39;&#39;&#39; signal. The latch circuit holds the &#39;&#39;&#39;&#39;authentic&#39;&#39;&#39;&#39; signal until circuitry responsive to the &#39;&#39;&#39;&#39;authentic&#39;&#39;&#39;&#39; signal performs a desired function, after which the credit card is indexed to a new position such that a different selected area of the coating of the credit card is processed to determine its authenticity.

United States Patent 1191 Swanberg et al.

1451 Mar. 5, 1974 APPARATUS FORTESTING A CREDIT CARD [75] Inventors:Melvin E. Swanberg, Upland; James M. Wilson, San Dimas, both of Calif.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: May 18, 1973 21 Appl. No.: 361,742

[52] US. Cl 250/209, 250/219 D, 250/219 DQ, 250/226, 194/4 R, 235/61.8R, 356/71 [51] Int. Cl. G0ln 21/30, 606k 9/08, G07f H06 [58] Field ofSearch356/7l; 250/219 DO, 209, 226,

250/219 D; 194/4 R; 340/149 A; 235/618 R,

Primary Examiner.lan1es W. Lawrence Assistant Examiner-T. N. Grigsby [57 ABSTRACT Apparatus for testing a credit card having a coating of asubstance which when treated sufficiently permanently and irreversablychanges from a first state having one characteristic of reflectivity forvisible light components incident thereon to a second state havingasecond characteristic of reflectivityfor the light components.Preferably, in the first state the substance is highly light reflectiveand reflects light of different wavelengths unequally, and in the secondstate thesubstance is light transparent. Treating of the substance isaccomplished by heating the substance, preferably with a high intensitylight beam. Authenticity of the credit card is achieved by firstmeasuring the amplitude of visible light components (colors) reflectedby the substance when the substance is treated initially, and by a laterspectral reflectance test after additional treating which, by sensingthe change in amplitude of a previously highly reflected visible lightcomponent, indicates that the substance has changed to the second statein response to the additional treating.

The authentification apparatus includes a light source for treating aselected area of the coating and a plurality of photoresponsive elementseach responsive to light of a selected wave length and connected inelectrical integration networks. The integration networks transforms theamplitude representative signals supplied thereto to time amplitudevarying signals which are supplied to flip-flop circuits of a logiccircuit which also includes at least one nor gate and a latch circuit.If the credit card is authentic, the amplitudes of the output signals ofthe integration networks increase and decrease in the proper sequence tocontrol the logic circuit such that it produces an acceptance orauthentic signal. The latch circuit holds the authentic signal untilcircuitry responsive to the authentic signal performs a desiredfunction, after which the credit card is indexed to a new position suchthat a different selected area of the coating of the credit card isprocessed to determine its authenticity.

10 Claims, 7 Drawing Figures PATENTEDIIAR 5 I974 SIIEEI 2 (IF 3 TOSTEPPING MOTOR 55 CONTROL CIRCUIT (BLUE) (GREEN) 'CL (RED) 0 FIG. 5

PATENTEBHAR 5 I974 SHEEI 3 [IF 3 SHUTTER CLOSES BURN SHUTTER OPENS I I II RED FIG. 7

I APPARATUS FOR TESTING A CREDIT CARD BACKGROUND OF THE INVENTIONConsumable credit cards have long been used as a means for purchasingservices in advance and at a reduced rate. For example, in the commutertransportation industry, multi-ride cards have been used extensively toprovide a reduced rate per ride, the cards being physically manipulated,notched or punched by an attendant each time they are used. Similarcards have been used in other multi-use service areas, such as cafeteriaservices, or vending machine services. These cards are generally made ofa soft material which allows them to become bent and defrayed.

A recent development in commuter transportation systems involves the useof automated ticket processing machines for entrance and exit gates atthe various stops along the transportation system. A commuting passengerusing the system will initially purchase, such as from a vendingmachine, a multi-ride ticket which on one side has various instructionsfor the use of the ticket and on the underside has a printed value grid.The ticket also has a magnetic, iron-oxide, recording strip on itsunderside, on which is magnetically recorded, by the vending machine,information such as the value of the ticket and the date.

To gain entrance to the transportation system, the passenger inserts theticket into the automatic entrance ticket machine at an entrance gatewhich includes a turnstyle. The pertinent functions of the ticketmachine are that it magnetically records the station location on themagnetic recording strip, opens the turnstyle to admit the passenger,and returns his ticket. No marks are made on the value grid. When thepassenger disembarks at his station, he places his ticket in theautomatic exit ticket machine at an exit gate which also includes aturnstyle. This ticket machine, and cooperating computer apparatus,determines the validity of the card and, from the magnetic recording, ifthe ticket has sufficient value for the ride just completed, places amark in the grid to show the degraded value of the ticket, opens theturnstyle, and returns the ticket. If the recording upon the ticketshows insufficient value for the ride when the ticket isplaced into theticket machine at the exit gate, the turnstyle will not open, and thepassenger must consult the station agent. The mark in the grid is onlyfor the information of the person owning the ticket; as far as theticket machines are concerned the value of the ticket is indicated bythe magnetic recordings thereon.

Another type of credit card used for commuter transport systems includesdielectric members which are laminated together and externally printedwith grid squares which indicate the worth of the ticket. Conductive inkmarks or strips underlie the rows of grids from edge to edge of thedocument. The member carrying the strips is thin, so that a marking too]impressed in a grid will electrically alter the conductivity of thestrip. When inserted into an exit control apparatus, the apparatusdetermines the number of uncut strips to ascertain the value of the cardwhich is rejected when an insufficient value is indicated.

One drawback of the above cards, described in detail in US. Pat. No.3,470,359, is that the cards are easily altered. Thus, it would befairly easy for a knowledgable person to copy the magnetic recordings ofthe firstdescribed card onto a used card, after mechanically erasing itsold recordings, or to place a similar recording on a ticket-sized card.Similarly, a knowledgable person could alter the conductivity of theconductive strips of the second-described card. In addition, thepreviously described cards do not provide the card user with a clearindication of the remaining value of a partially-used card, and they areexpensive to manufacture.

Another area in which automated apparatus has been used to distinguishbetween real and counterfeited documents is in currency changingmachines and vending machines. In one common type of such apparatus,described in US. Pat. No. 3,480,785, the document to be inspected ispositioned to receive light, and a plurality of sensors are positionedto receive light reflected from preselected discrete areas on onesurface of the document and to provide signals in response to thespectral content thereof. Such signals must be within predeterminedamplitude limits for the apparatus to accept the document as authentic.Although these systems may provide satisfactory results for currencycashing, they would not be usable with consumable credit cards, becausethese systems do not provide an indication of the present value of thecard after partial use of the card and do not alter the characteristicsof the document tested in any way.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide an improved apparatus for testing the validity of acredit card.

A further object of the present invention is to provide apparatus fortesting the validity of selected, discrete areas of a credit card.

A still further object of the present invention is to provide apparatusfor testing the validity of a credit card which changes its opticalcharacteristics when treated.

In accordance with the invention, apparatus is disclosed for testing theauthenticity of a credit card which is provided with a coating of asubstance which, when treated sufficiently, is permanently altered orchanged from a first state having one characteristic of opticalreflectance for light components incident thereon to a second statehaving a different characteristic of optical reflectance for the lightcomponents. Since treating (as by absorbing heat from an incident lightbeam) can be applied progressively to selected areas of the coating, andthe change in the optical reflectance of the treated areas is permanent,not temporary or reversible, and appears as a darkening of those areasof the coating, optical inspection of the credit card, by man ormachine, provides an indication of the remaining credit worth of thecredit card. A light absorptive strip is provided on one side of thecoating to enhance the optical contrast between the areas of the coatingthat are in the first state and areas of the coating that are in thesecond state. A patent application having claims directed to the creditcard and method of testing the credit card, entitled Credit Card andassigned to'the same assignee as the present invention, was filedconcurrently with this application.

Authentication of any area of the alterable coating of the credit cardis achieved by first measuring the amplitude of visible light components(colors) reflected by the areas of the alterable coating when that areais in the first state and, thereafter, by measuring any change inamplitude of a previously reflected visible light component, thereby toindicate that the area has changed to the second state. Theauthentification apparatus includes a light source for treating aselected area of the coating and a plurality of photoresponsive elementseach responsive to light of a selected wave length. The photoresponsiveelements form parts of electrical integration networks which transformthe amplitude representative signals supplied thereto to time-amplitudevarying signals which are supplied to a logic circuit. The logicelements of the logic circuit are gated if the time-amplitude varyingsignals occur in the proper sequence, thereby producing an authenticsignal which is held by a latch circuit forming part of the logiccircuit. Thus, if the components of the reflected light have the correctamplitude relationship during both measurements, an output signal isgenerated which permits the credit card to be accepted and a single useto be made of the credit card. With each valid use of the credit card,and where multiple use of the card is desired, the credit card isindexed to a new position, either manually by the user or automatically,such that an adjacent area is tested. If the result of eithermeasurement is incorrect for all areas of the credit card, the creditcard is not accepted.

Other objects of the invention will become readily apparent to thoseskilled in the art in view of the following detailed disclosure anddescription thereof, especially when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of thecredit card of the present invention.

FIG. 2 is a perspective view of the authentification apparatus used withthe credit card of FIG. 1.

FIG. 3 is a schematic view of the optical system of the apparatus ofFIG. 2.

FIG. 4 is a schematic diagram of one portion of the electricalcomponents of-the apparatus of FIG. 2.

FIG. 5 is a schematic diagram of the logic circuit of the apparatus ofFIG. 2.'

FIG. 6 illustrates waveforms produced during testing of the alterablesubstance forming part of the credit card of FIG. 1.

FIG. 7 is a schematic diagram ofa motor stepping circuit than can form apart of the apparatus of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention isapplicable to all areas where credit cards are used to controlunattended apparatus. Specific areas in which the invention is useful isin the field of commuter transportation and vending machines. Theinvention is particularly useful in the field of copy and duplicatingapparatus. In the latter application, the customer would purchase thecredit card from a librarian, book store, supermart, etc. at a reducedrate per copy, insert the credit card into a copy machine, dial thenumber of copies desired (up to the maximum allowed by the card), andpress the print button. If the credit card is authentic and has value tocover the number of copies dialed, the customer receives his desirednumber of copies and his card is returned with a dark area on it foreach copy made. The dark areas allow the customer to tell at a glancehow many copies worth remain on the card and prevents the unattendedapparatus from producing another copy chargeable to a previously usedarea. When the card has been exhausted, a new card is purchased. Someadvantages of this type of credit card purchase are reduced rate percopy, credit card convenience, and eliminated coin box pilferage.

Referring now to FIG. 1 of the drawings, the credit card 2 typicallycomprises two layers 4 and 6 of clear vinyl plastic or other stifftransparent material. Layers 4 and 6, typically 0.025 inch and 0.005inch thick, respectively, are laminated together, such as by atransparent, pressure sensitive adhesive. A strip of light abosrptive(black) paper 8, preferably about 0.005 inch thick, is positionedbetween layers 4 and 6. A thin, preferably 0.001 inch to 0.005 inchthick, coating 10 of a heat-alterable substance is applied to onesurface of paper 8. Coating 10 can be applied by masking all but thepaper 8 and spraying the heat-alterable substance onto the exposedsurface of paper 8. Obviously, the application of coating 10 is achievedprior to laminating together layers 4 and 6.

The substance used as coating 10 is selected from a group which havedifferent optical reflectance characteristics at different temperatures,that is, substances that have a given spectral reflectancecharacteristic under one condition, that is, within a first range oftemperatures, and a different spectral reflectance characteristic undera second condition, that is, within a second range of temperatureshigher than the first range of temperatures. The transition temperaturefrom the first range to the second range is referred to as the criticaltemperature, or burn temperature. A preferred group of substances ofthis type is sold by Tempil Corporation of South Plainfield, New Jersey,under the trademark Tempilaq. These substances reflect light frequencycomponents (colors) having desired amplitudes when within the firstrange of temperature and, when heated to within the second range oftemperatures, do not reflect in large amplitude at least one of thepreviously present light frequency components. Specifically, one suchsubstance, that is, Tempilaq" No. E, reflects a large amount of bluelight, a smaller amount of green light, and a still smaller amount ofred light (the reflected light appearing blue to the human eye) when ata temperature less than 175 F but very little blue light when heatedbeyond the burn temperature of 175 F. Burn" or change of state takesless than 5 milliseconds. Another acceptable group of materials forcoating layer 10 is sold by the William Wahl Corporation of SantaMonica, Cal., under the trademark Temp-Plate.

Since in one of it intended purposes, the credit card I willprovide formultiple credit charges, adjacent areas of the coating 10 can be heatedfor each credit charge. Heating of the separate areas is achievedpreferably by indexing the credit card horizontally or vertically,either manually or by automated apparatus. If desired, boarder stripscan be provided between adjacent areas of the coating 10 to isolate themsuch that only one area at a time is heated, such as by a high intensitylight beam.

Due to the change in state and associated change in spectral reflectance(amplitude of colors reflected) of coating 10 when heated beyond thecritical temperature, two separate tests can be performed to check thevalidity of the credit card. The first test analyzes or measures theamplitude of light components (colors) reflected from coating when it isin its first stage, that is, when it is below 175 F in the case ofTempilaq No. l75F. This test data is integrated to sharply define theamplitudes of the reflected colors and then the waveforms indicative ofthe color amplitudes are supplied to logic circuitry, described indetail hereinafter, which provides a first test signal indicative of theproper color amplitudes. The second test provides an indication that thecoating 10 has changed state or burned due to continued heating, thatis, that the amplitude of one of the reflected colors, blue in the caseof Tempilaq" No. 175F, has decreased greatly. This decrease in amplitudeand the first test signal are utilized by the logic circuitry to providea signal indicative of an authentic credit card. The change of state ofa heated area of coating 10 also provides a permanent and irreversibleindication, to the user and to the associated authentificationapparatus, that the area of the coating has been used for a creditpurchase. In the case of Tempilaq" No. 175F, a solid (or possibly supercooled liquid) is formed after cooling from about 175 The substance ofcoating 10 is different from liquid crystals used to produce temporarydisplays, as described in US. Pat. Nos. 3,637,291 and 3,524,726.Although the substances described in the above patents evidence twochromatic states, i.e., a first translucent state and a second opaquestate, when heated to a predetermined temperature, the substance must beable to reverse states to provide the desired change in visable display.This reversal is accomplished by the removal of the heat. It istherefore necessary to continuously apply energy to the liquid crystalmaterial in order to display the images for extended periods of time,since the change in light-reflecting properties is not stable.

The manner in which the credit card 2 can be used and tested is bestexplained by reference to FIGS. 2 and 3 which show the novel apparatusfor testing the validity of credit card 2. A lamp 14, with the aid ofacollecting mirror 16, projects a high intensity light beam through lensassembly 17 toward a credit card holder 18 which has channels (notshown) for holding the credit card. Lamp 14 can be a l2-volt, ISO-watttungsten halogen lamp. An apertured shutter 20 is positioned between thelamp l4 and the holder 18 to intercept the light beam at all timesexcept when the validity tests are to be performed. To restrict the areaof the light beam impinging upon card 2 when it is between the supportchannels, an apertured mark 19 is positioned adjacent the holder 18 onthe side thereof facing lamp 14.

In operation, when the credit card 2 is inserted between the channels ofholder 18, a switch is tripped which permits energization of a solenoid22 which moves shutter 20 to the right, thereby allowing light to beprojected through the aperture in shutter 20 and onto a selected area ofcoating 10. Timing means (not shown) are provided such that shutter 20is in the light transmissive position for the duration of testing, abouteight tenths ofa second when Tempilaq No. 175F is used as the substanceof coating 10. If desired, a shoulder, keyway, or other suitableindexing means may be included in the structure of credit card 2 torequire a specific orientation of the card before it may be entered intothe holder channels, thus obviating the user visually orienting the cardfor face-up operation.

As previously mentioned, when coating 10 is Tempilaq No. 175F, initialheating (heating below 175 F) produces a spectral reflectance spectrumhaving a large amplitude blue component, a smaller amplitude greencomponent, and a still smaller amplitude red component. When strip 10 isheated sufficiently, about 175 F, which occurs after about 0.7 secondsof exposure to a high intensity light beam, such as produced by a watttungsten halogen lamp, the coating 10 burns (changes state) with theresult that coating 10 becomes transparent thereby exposing the highlylight absorptive strip 8 to the photoconductors 28, 29 and 30 wherebythe amplitudes of the reflected light (particularly blue light) decreaserapidly. These colortemperature characteristics of coating 10 are usedto produce two test signals, as now will be explained.

Positioned adjacent to the support 18 is a photoconductor assembly whichincludes three light filterphotoconductor combinations. Specifically,photoconductors 28, 29, and 30 cooperate with filters 32, 33, and 34,respectively, which (when coating 10 is Tempilaq No. l75F) transmitblue, green, and red light, respectively. Accordingly, only the bluecomponent of the light reflected by coating 10 of credit card 2 isincident on photoconductor 28; only the green component of the reflectedlight is incident on photoconductor 29; and only the red component ofreflected light is incident on photoconductor 30. A funnel-shaped shield36 is positioned adjacent the filters 32, 33, and 34 and the credit cardsupport 18 to prevent stray light (light not reflected by a heated areaof coating 10) from contributing to the conductivity of thephotoconductors 28, 29, and 30. If desired, light conducting fibers maybe used to conduct the reflected light to the location of thefilter-photoconductor combination as a further preventative againsterroneous signals produced by stray light.

Photoconductors 28, 29, and 30 form parts of conventional integrationcircuits 40, 41, and 42, respectively, as shown in FIG. 4. With thecoating 10 of Tempilaq No. F having the spectral reflectance sequencepreviously set forth, that is, reflectance of a large amount of bluelight, a smaller amount of green light, and a still amaller amount ofred light prior to burn, with a decrease in the amplitude of thesecolors reflected by coating 10 after it burns or changes state, theoutput waveforms of the integrators 40, 41 and 42 will be as shown inFIG. 6. As indicated by FIG. 6, the output waveform of integrator 40(blue light) reaches a high value of amplitude (due to the largeamplitude of blue light reflected) prior to the time that the outputwaveforms of integrators 41 (green light) and 42 (red light) reach ahigh level, with the output waveform of integrator 41 (green light)reaching a high value before the output waveform of integrator 42 (redlight) reaches a high value (due to the larger amplitude of green lightreflected than red light reflected). FIG. 6 also shows that the outputwaveform of integrator 40 decreases rapidly once the strip 10 burns orchanges state.

The output signals of integrators 40, 41 and 42 are supplied to inputterminals of a logic circuit (FIG. 5) which is one form of logic circuitthat can be used to make the determination of whether the amplitudes ofthe light components (colors) reflected by coating 10 is proper whencoating 10 is in the first state (first test), and whether the amplitudeof the blue component of the reflected light diminishes rapidly whencoating 10 is heated sufficiently to change state (second test).Referring specifically to FIG. 5, the output of integrator 40 (bluelight waveform) is supplied to the D input terminalof a flip-flop 50 andto one input terminal of a NOR gate 52. The output of integrator 41(green light waveform) is supplied to the CL (clock) input of flipflop50. The Q or'high voltage output of flip-flop 50 is coupled to the Dinput of a flip-flop 54. The output signal of integrator 42 (red lightwaveform) is supplied to the CL (clock) input of flip-flop 54, the Qoutput of flip-flop 54 being supplied to another input of NOR gate 52.The third input to NOR gate 52 is connected to a dropping resistor 56which has its non-ground side connected to a dc source through a switch57 which is open only when shutter 20 is permitting light from lamp 14to illuminate coating or an area thereof. The output terminal of NORgate 52 is connected to an input terminal of a NOR gate 58 which formspart of a clamping circuit 60. Circuit 60 also includes a NOR gate 62which has its output signal feedback to a second input terminal of NORgate 58. The output terminal of gate 58 is connected to an inputterminal of gate 62, the other input terminal of gate 62 being connectedboth to the non-grounded side of a dropping resistor 64 and to a dcsource via a switch 66.

In operation of the circuit of FIG. 5, the output of NOR gate 50 will bepositive only if all the input signals thereto are negative. This willoccur only when the spectral pulses occur in the sequence shown in FIG.6' and the coating 10 burns. In the proper sequence, the leading edge ofthe green signal will provide a clock pulse while the blue signal ispositive, producing a positive signal at the output of flip-flop 50,thus arming flipflop 54. The leading edge of the red signal clocksflipflop 54 after it is armed, producing a negative signal at the lowerinput terminal of gate 52. Shortly thereafter, the blue signaldecreases, producing a negative going appear at the bottom inputterminal of gate 52. Similarly, if the leading edge of the integratedgreen signal did not attain a high value while the integrated bluesignal was at a high value, the flip-flop 54 would not be armed, and itwould not produce a negative pulse upon will be devided into discreteareas, each area representing a single credit purchase. In the case ofmultiple purchases, the testing equipment would include apparatus(indicated generally as 70 in FIG. 2) for transporting the credit cardhorizontally and vertically such that the light from lamp 14 can be madeto fall sequentially on adjacent areas of the coating 10 of credit card2. When the credit card is used with a copying of duplicating apparatus,the credit card would be indexed such that the desired number of copiescan be made.

Obviously, the testing apparatus would include apparatus (not shown)which would index the tranport system to the first unburned area of thecredit card. This could be achieved by a photoconductor positionedadsignal at the middle input of gate 52. Since the signal applied to thetop input terminal of gate 52 is always negative (ground) when theshutter 20 is open (about 0.8 seconds), the proper sequence of colorsproduces negative pulses at all three input terminals of NOR gate 52 andthus a positive signal at the output terminal of NOR gate 52. The latchcircuit 60 provides a permanent indication of the positive signal at theoutput of gate 52. The output of gate 62 of the latch circuit 60 iscoupled to control circuitry (not shown). which reacts only to apositive signal to induce operation of a a machine, such as a copier.When the machine has cycled, the switch 66 is closed, providing a highvoltage signal to the lower input of gate 62, with the result that theoutput of gate 62 becomes negative. NOR gate 52 is reset by the closingof switch 57 when the shutter 20 closes.

If the coating 10 did not burn or change state, that is, did not ceaseto reflect a large amount of blue light, the input signal to the middleinput terminal of gate 52 would remain positive and the output signalthereof would not become positive. If the amplitude of the reflectedcolors, and accordingly the timing sequence of pulses produced by theintegrator networks 40, 41, and 42, did not occur as desired, forexample, if the amplitude of the red signal was too large and the edgeof the high voltage signal produced by integrator 42 occurred beforeeither the integrated blue or green signal attaining a high value, theflip-flop 54 would be clocked prior to being armed, and a negative goingsignal would not jacent the coating 10. If a light beam, either producedby lamp 14 or by another light source, incident on an area of coating 10does not provide a minimal amount of reflected light (incident on thephotoconductor) within a few tenths of a second, indexing apparatuswould move the credit card holder to a new position such that light nowfalls on an adjacent area of coating 10. A typical stepping motorcontrol circuit which would be used to move or index the credit cardwhen it is intended for multiple purchases is shown in FIG. 7. Each timethat switch- 57 closes the relay switch R is closed, momentarilyresulting in the conduction of controlled rectifier Q and, as a result,the conduction of controlled rectifier Q The current flow through themotor control winding, as a result of conduction of controlled rectifierO is sufficient to produce one increment of revolution of a motorshaftwhich is coupled to holder 18, such as through an appropriate geartrain.Accordingly, the holder 18 would move one increment, depending uponthesize of the descrete areasof the coating 10, each time thatthe shutterswitch 57 is closed.

1 In addition to defining the second spectral reflectance aftercoatingl0 has changed to a transparent liquid (and then to a solid oncooling), highly light absorptive strip 8 serves two other functions.First, it absorbs radiant energy incident thereon thereby reducing thetime necessary to heat coating 10 to the burn" temperature. Second, itabsorbs the liquid of coating 10 when it changes to a liquid statethereby helping to prevent the possibility of mechanically manipulatingthe substance of coating 10 once it has changed state.

While the present invention has been described with reference topreferred arrangements, it will be understood to those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the true spirit and scope ofthe invention. Specifically, a different color light absorptive strip 8could be used instead of black. If strip 8 were red, the secondauthenticity test would indicate that the amplitude of blue lightreflected by the card had decreased substantially, while the magnitudeof red light reflected had increased substantially. In addition, thebandwidth of the light filter can be changed to correspond to the lightcolors used to test the validity of the credit card, and the coating orany area thereof can be heated by apparatus other than lamp 14.Additional filters could be included between the lamp l4 and the creditcard holder which would permit only the passage of infrared light andlight of those colors used in the testing of the credit card.

What is claimed is:

1. Apparatus for testing the authenticity of a credit card having alayer of a substance with a first optical reflectance characteristicwhen within a first temperature range, and a second optical reflectancecharacteristic when heated to a temperature beyond said firsttemperature range, comprising:

first means for heating said substance through at least a portion ofsaid first temperature range and thereafter to beyond said firsttemperature range,

second means for projecting a high intensity beam of light onto saidsubstance,

a plurality of photoelectric assemblies positioned adjacent saidsubstance, each of said photoelectric assemblies responsive toelectromagnetic radiation of a different frequency reflected by saidsubstance,

a plurality of networks, each including a component of saidphotoelectric assemblies, for transforming the electromagnetic radiationof said different frequencies to time-amplitude varying electricalsignals, and

logic means coupled to said networks for determining if saidtime-amplitude varying electrical signals are within desired amplituderanges when said substance is heated through said first temperaturerange and beyond said first temperature range.

2. The apparatus of claim 1 wherein said first and second means is asingle high intensity light source.

3. The apparatus of claim 1 wherein said networks are electricalintegration networks.

4. The apparatus of claim 3 wherein each of said photoelectricassemblies includes a light filter responsive only to light ofa givenfrequency and a photoconductor positioned to receive only light passingthrough said filter associated therewith, said photoconductors beingcomponents of said electrical integration networks.

5. The apparatus of claim 4 wherein said logic means includes anelectrical latch circuit.

6. The apparatus of claim 5 wherein said logic means further includesfirst and second flip-flop circuits and a multi-input electronicgate,the high voltage output of said first flip-flop is coupled to aninput of said second flip-flop, and the low voltage output of saidsecond flipflop is supplied to an input of 'said gate, said plurality ofphotoelectric assemblies being three in number with the output of two ofsaid assemblies being supplied to the arming and clock terminals of saidfirst flip-flop,

and the output of said other photoelectric assembly being supplied tothe clock input of said second flip- 7. The apparatus of claim 6 whereinsaid apparatus includes means for preventing stray light from affectingsaid photoelectric assemblies.

8. Apparatus for testing the authenticity of areas of a layer of asubstance having a first optical reflectance characteristic when withina first temperature range and a second optical reflectancecharacteristic when heated to a temperature beyond said firsttemperature range, said substance forming part of a credit card,comprising:

means for heating one area of said substance through at least a portionof said first temperature range and thereafter beyond said firsttemperature range,

means for projecting a high intensity beam of light onto said one areaof said substance,

' a plurality of photoelectric assemblies positioned adjacent saidsubstance, each of said photoelectric assemblies being responsive toelectromagnetic radiatiori of a different frequency reflected by saidarea,

a plurality of networks, each including a component of saidphotoelectric assemblies for transforming the electromagnetic radiationof said different frequencies to time-amplitude varying electricalsignals,

logic means coupled to said networks for determining if saidelectromagnetic radiation of different fre-- quencies reflected by saidarea is within desired amplitude ranges during both said firsttemperature range and beyond said first temperature range, and

means for moving said credit card after said area of said substancehasbeen tested so that another area of said credit card can be tested.

9. The apparatus of claim 8 wherein each of said photoelectricassembliesincludes a filter responsive only to light of a given frequency and aphotoconductor positioned to receive only light passing through saidfilter associated therewith.

10. The apparatus of claim 9 wherein said logic means includes first andsecond flip-flop circuits and a multi-input electronic gate, the highvoltage output of said first flip-flop is coupled to an input of saidsecond flip-flop, and the low voltage output of said second flipflop issupplied to an input of said gate, said plurality of photoconductorassemblies being three in number with the output of two of saidassemblies being supplied to the arming and clock terminals of saidfirst flip-flop, and the output of said other photoconductor assemblybeing supplied to the clock input of said second flipflop.

1. Apparatus for testing the authenticity of a credit card having alayer of a substance with a first optical reflectance characteristicwhen within a first temperature range, and a second optical reflectancecharacteristic when heated to a temperature beyond said firsttemperature range, comprising: first means for heating said substancethrough at least a portion of said first temperature ranGe andthereafter to beyond said first temperature range, second means forprojecting a high intensity beam of light onto said substance, aplurality of photoelectric assemblies positioned adjacent saidsubstance, each of said photoelectric assemblies responsive toelectromagnetic radiation of a different frequency reflected by saidsubstance, a plurality of networks, each including a component of saidphotoelectric assemblies, for transforming the electromagnetic radiationof said different frequencies to time-amplitude varying electricalsignals, and logic means coupled to said networks for determining ifsaid time-amplitude varying electrical signals are within desiredamplitude ranges when said substance is heated through said firsttemperature range and beyond said first temperature range.
 2. Theapparatus of claim 1 wherein said first and second means is a singlehigh intensity light source.
 3. The apparatus of claim 1 wherein saidnetworks are electrical integration networks.
 4. The apparatus of claim3 wherein each of said photoelectric assemblies includes a light filterresponsive only to light of a given frequency and a photoconductorpositioned to receive only light passing through said filter associatedtherewith, said photoconductors being components of said electricalintegration networks.
 5. The apparatus of claim 4 wherein said logicmeans includes an electrical latch circuit.
 6. The apparatus of claim 5wherein said logic means further includes first and second flip-flopcircuits and a multi-input electronic gate, the high voltage output ofsaid first flip-flop is coupled to an input of said second flip-flop,and the low voltage output of said second flip-flop is supplied to aninput of said gate, said plurality of photoelectric assemblies beingthree in number with the output of two of said assemblies being suppliedto the arming and clock terminals of said first flip-flop, and theoutput of said other photoelectric assembly being supplied to the clockinput of said second flip-flop.
 7. The apparatus of claim 6 wherein saidapparatus includes means for preventing stray light from affecting saidphotoelectric assemblies.
 8. Apparatus for testing the authenticity ofareas of a layer of a substance having a first optical reflectancecharacteristic when within a first temperature range and a secondoptical reflectance characteristic when heated to a temperature beyondsaid first temperature range, said substance forming part of a creditcard, comprising: means for heating one area of said substance throughat least a portion of said first temperature range and thereafter beyondsaid first temperature range, means for projecting a high intensity beamof light onto said one area of said substance, a plurality ofphotoelectric assemblies positioned adjacent said substance, each ofsaid photoelectric assemblies being responsive to electromagneticradiation of a different frequency reflected by said area, a pluralityof networks, each including a component of said photoelectric assembliesfor transforming the electromagnetic radiation of said differentfrequencies to time-amplitude varying electrical signals, logic meanscoupled to said networks for determining if said electromagneticradiation of different frequencies reflected by said area is withindesired amplitude ranges during both said first temperature range andbeyond said first temperature range, and means for moving said creditcard after said area of said substance has been tested so that anotherarea of said credit card can be tested.
 9. The apparatus of claim 8wherein each of said photoelectric assemblies includes a filterresponsive only to light of a given frequency and a photoconductorpositioned to receive only light passing through said filter associatedtherewith.
 10. The apparatus of claim 9 wherein said logic meansincludes first and second flip-flop circuits and a multi-inputelectronic gate, the high voltage Output of said first flip-flop iscoupled to an input of said second flip-flop, and the low voltage outputof said second flip-flop is supplied to an input of said gate, saidplurality of photoconductor assemblies being three in number with theoutput of two of said assemblies being supplied to the arming and clockterminals of said first flip-flop, and the output of said otherphotoconductor assembly being supplied to the clock input of said secondflip-flop.